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The BAT Bone and KK2

#1
Hi all, i've got my bat bone all set up and almost flying great ( lot of practise by me needed nothing like a plane lol)

but main question is when i hard throttle up the tri keeps trying to back flip because the 2 front motor over power the back one, what setting on the KK2 do i need to alter

Thanks in advance.....

Even fitted my spare motors to see if that was the issue
 

colorex

Rotor Riot!
Mentor
#2
You need to balance your multicopter. The weight center is moved towards the back, putting extra unnecessary strain on it.

Move the battery forward, I use the front velcro hole and I mount the battery so that it protrudes about half an inch from the front of the bat bone frame. Then test and see where you need to adjust the CG.
 

colorex

Rotor Riot!
Mentor
#4
being that there is only so much landscape available on a tri, even the bat bone- you may to adjust you mixer settings on top of your cg, cg is relevant but not always the answer. you can lower power to 2 front motors and/or raise power to the rear.
David goes over this in the new bat bone vtail quad video.http://www.youtube.com/watch?v=yspYWf4U4Gs&feature=c4-overview&list=UU9zTuyWffK9ckEz1216noAw
Good Luck!
-5
A quad should always be balanced before adjustment. You could just slap the battery wherever you want and correct for that with the mixer, but that would put unnecessary strain on your copter. So please balance first as much as you can, then head over to the mixer.
 
#5
yea balance as best as you can and WHEN that does not work- because it wont. use your mixer. we are talking a tri here not a quad- the reference to davids video was only for the mixing instruction for this particular situation. i dont have 5k plus posts here but i do have 2 tricopters and im dealing with the exact same situation. you can rebalance all day long but when it all boils down you still have 1 motor vs 2 in the front for pitch control.
......patiently waiting for results from proxy.
-5
 

colorex

Rotor Riot!
Mentor
#6
May I correct myself:

A quad multirotor should always be balanced before adjustment.
May I add that on a tricopter the balance point should be forward of the center of the motors.

when it all boils down you still have 1 motor vs 2 in the front for pitch control.
Which is why IMHO you should move the battery forward to put less strain on the back motor.

Number of posts doesn't matter. I don't have two tricopters, but I had an RCExplorer tricopter that I took apart and rebuilt to the Bat Bone frame.

I had the same issue on my first and second tricopter (one with KK1 and the new with KK2) and I fixed the pitching-back-when-throttle-up issue by moving the battery forward. I have not touched the mixer editor yet my tricopter flies fine.

Let's say your frame forces you to put the battery on the rear boom, making the rear motor spin faster (say 60% when the front spin at 40%) to hold up the battery. You can of course correct the mixer settings so the tricopter rises level in a throttle-up, but that motor is going to have only 40% available for the lift, while the other motors have 60% available. The board will push your back motor to 100%, but in order to keep your copter level it will only push the front motors to 80%.

BTW This is just a humble reply, not an attack :)
 

CrashRecovery

I'm a care bear...Really?
Mentor
#7
Hi all, i've got my bat bone all set up and almost flying great ( lot of practise by me needed nothing like a plane lol)

but main question is when i hard throttle up the tri keeps trying to back flip because the 2 front motor over power the back one, what setting on the KK2 do i need to alter

Thanks in advance.....

Even fitted my spare motors to see if that was the issue

if its only when you punch it, go into your I believe stick settings and give the tail a higher percentage for throttle then the front two
 
#8
well fair enough color- there isnt much room in front of center of the motors on the bat bone- they center directly on top of the fc if the booms are all the same length.
stick scaling only affects how the fc interprets the signal from the tx, not variables between motor channels.
i would agree that balance is important but with the nature of the tricopter PITCH power ratio (2 vs 1) you can only move so much weight forward to compensate for the lack of having 1 less motor in the rear- this is where mixer settings would come in. you can directly change the amount of power given to any given channel on the fc.
-5
also waiting to hear any results from proxy
 

colorex

Rotor Riot!
Mentor
#9
Specifically for the Bat Bone and a 2200mAh battery this is how I mount my battery.

As you can see it's not the way you would expect to mount it, but it solves the problem with no mixing. At least for me it does :)

 
#11
Related topic. This is for David. How is it you were able to control the V-Tail so precisely using the KK2 board for FPV on the Bat Bone video?? I'm an intermediate heli flyer. I'm flying my first multicopter (Simple T-Copter) that I built myself using the KK2 and am trying to learn to fly FPV with it. I'm getting the hang of flying without goggles (non-FPV). But, with goggles, every flight is a cliff hanger! I'm now planning to update the KK by switching to an APM or similar platform.
 
#12
I had the same problem with my Bat Bone tricopter build. I moved my 3S 3000Mah battery as far forward as I possibly could, and then made some adjustments in the Mixer Settings on the KK2. If memory serves me, I believe setting M1 and M2 to 85 for throttle pretty much leveled it out.

I'm new to multirotors myself, but after some recent research and reading about PI gains, you might try flying with and without Auto Level enabled and see if things change. Again, based on reading; if your PI gain settings are off, and Auto Level is on, your craft might continuously drift in one direction as it tries to come back to level.

I found this Flite Test article: http://flitetest.com/articles/p-i-and-sometimes-d-gains-in-a-nutshell

and this youtube video: https://www.youtube.com/watch?v=f0Bh3fMGHbM&index=10&list=FL0LhD3HYlDOHFWY8pG_vK0g

extremely helpful.